Passions of mine include Wheatears (Oeneanthe, a genus
in the family Muscicapidae) and one of particular interest is the elegant,
comic and enigmatic Black Wheatear. Here in my mountains I can connect with
these friends at any time I want, through the depths of winter through to high
summer. Nothing is more relaxing and holds my fascination more than observing
males demonstrate strength and attraction to watching females. The males
decorate nesting places with stone platforms, individual stones can weigh up to
22gms and the older the male, the heavier these stones can be. It appears these
demonstrations of strength cement bonds between pairs and also advertise the
superiority of some older males.
Largely resident in my area (Serrania de Ronda), with
only some altitudinal dispersal noted, my Black Wheatears pair for life. The
pair will defend their territories against interlopers and this more often than
not involves younger birds seeking to usurp the resident pair. However, there
appears to be a certain amount of tolerance displayed towards neighbouring
pairs and an overlapping of territories, perhaps a recognised buffer zone
between territories. Monogamy too seems to be social rather than sexual,
permissiveness being observed by both male and females.
Study Area
With
Ronda being the centre point, the study area takes in most of Parques Natural
Grazalema and Sierra de las Nieves. Additional principle mountain ranges are
also included. The study area chosen, see accompanying map and grid, has been
determined by suitable and likely habitat for all three species of summer
resident Oenanthe. The area has, to some degree, been increased to account for
the more isolated populations of the localised Oenanthe leucura. Otherwise the
area covered is limited by the physical possibilities to adequately trek any
larger an area in the time available. As the study progresses, boundaries may
change, especially if certain areas are virtually void of any Oenanthe species
and other areas bordering the study area contain worthwhile numbers of
principle study species. Initially the area is to be divided into populations
West, Central and Eastern. Some conjecture in determining these divisions
arises, but until experience teaches otherwise, then a choice had to be made as
a starting point.
Typical Black Wheatear territory/habitat |
Objects of The Project/Study
By the
capture of adult birds for ringing and also the ringing of pullus, the main
objects are to establish site fidelity of adult birds and dispersal or fidelity
of young returning adult birds. In the case of Oenanthe leucura the
additional objects are for monitoring any post juvenile dispersal and
population exchanges between various isolated breeding areas. Of course in
addition to the main objects of the study, the equally important objectives
will be to establish population densities and provide a basis for monitoring
future population dynamics within the area. It should prove very compatible to
ring secondary study species belonging to the same family group, as these are
likely to be discovered breeding within the same principle study area and
habitats. Again, population densities alone should provide critical information
for future reference and comparison.
Methodology
For
the purposes of the project’s objectives it is essential to use, in addition to
standard rings, colour rings for the principle species of this study. The use
of colour rings, coded for different areas within the study area, will give
visual aid to monitoring site fidelity and population movements.
It
is envisaged, that two colours per area are used, one for adult birds and
another for pullus (essential for establishing whether juvenile displacement
occurs). In all cases only one colour ring would be fitted to a single bird. In
all six colours for rings will be needed, three sub-regional population studies
with two colours for each area ( 1 = Adults 2 = Pullus). Each and every
discovered breeding bird of all three Oenanthe species will be ringed where
possible. The use of baited (mealworm) spring traps will be used for adult
birds. Nestlings, where safely accessible, will be ringed at the nest. All
captured breeding adult birds will be ringed, aged, overall wing measurement
taken and then released. Because of the sensitivity of ringing breeding adult
birds at the nesting area, then birds need to be released within the minimum
time necessary. The use of colour rings would appear the only sensible way to
monitor site fidelity and juvenile displacement/dispersal. Where population
densities require (single pairs or small to large colonies), then individual
sites will be named within any one grid reference. Each grid will be scaled
into quarter sections i.e. A1, A2 northern half and A3, A4 southern half and
visited, dependant on suitable habitat, during March through to the end of
August. Each suitable quartered grid section will be visited at least once per
month.
Initial reservations
and conclusions
Without
doubt the size of area within the chosen boundaries is and will remain a
mammoth undertaking, not to mention physically demanding for a solitary study.
With time the area requiring coverage will be less due to the absence, in
certain areas, of the principle study species. Access to certain areas within
the boundaries may be restricted and sometimes prohibited by landowners, which
could in theory devalue the project to a degree. The zoning of the area into
three parts may have to be reviewed with experience of any biased findings i.e.
small distances involved for displaced first year breeding adults. However,
this may be recognised and compensated for by the fragmentation of the main
grids into four sections and retrapping previously ringed individuals.
It
cannot be in doubt, that a study of this nature will enhance knowledge of local
requirements for the three main study species. Also and as an offshoot from
this main study, other species will be recorded and impressions given to
overall population densities for several species. If past experience is any
guide, then a few and maybe pleasant surprises could be expected. In one such
experience, Oenanthe oenanthe within an area of moorland (Bodmin Moor UK) was
given a population of no more than 50/60 pairs maximum. Upon species-specific
study and ringing, this 10 x 10 square kilometre Moor was discovered to contain
450 + pairs! The figure was later supported by UK Nature Conservation Council
funded Tetrad Study.
The Study Area is vast and fragmented in places |
Collalba Negra Black Wheatear Oenanthe
leucura
Field
Characters:
General.
Largest of the breeding Oenanthe in Europe. Unmistakable black plumage
with white rump, under tail coverts and tail. Tail broadly tipped black forming
typical ‘T’ shape characteristic of Oenanthe occurring in Europe (O.hispanica
not so pronounced). In flight appears heavy with typically shallow rapid wing
beats, reminiscent of Stonechat S.torquata. Strong flight only observed
whilst in pursuit of or chased by other territorial members of Turdidae i.e.
Blue Rock Thrush, or when being chased by predator. Favours rocky and
mountainous areas. Takes readily to tall scrub or tree as song or lookout post.
Adult Male : 2nd winter males black body
feathers. Wing coverts black, primaries and secondaries black with very slight
rich deep brown fringing to leading edges, becoming darker with age. Upper and
lower tail coverts white, central tail feathers 2/3rds black, outer tail
feathers white with outer 3rd black, the black forming a typical ‘T’
shape for Oenanthe sp., but even more pronounced than O. oenanthe.
1st winter and summer males are typically brown/black body feathers
and rich dark brown wing feathers (lesser coverts and some medium coverts are
black), deep brown outer edges tail outer tail feathers and to 2/3rds of
central tail feathers.
Adult Female : 2nd winter females deep
brown/black body feathers. Wing coverts typically the darker than colour of
body feathers. Primaries and secondaries dark brown, not black. Under and upper
tail coverts cream to white, central tail feathers 2/3rds deep brown, outer
tail feathers white/cream with outer 3rd deep brown, pattern as
male. 1st winter and summer females are typically lighter brown,
almost juvenile rust coloured on head and mantle.
Juvenile : Until post-juvenile moult, body
feathering is rust brown, contrasting with
wing coverts and flight feathers, which are brown. Rust coloured
fringing to body feathers abrade and slowly reveal basal brown ground colour to
plumage.
Habitat.
Mountain and hillside slopes, generally rocky outcrops and scree, but typically
with an area of over/grazed pasture or bare area. Tolerant of sparse tree or
scrub cover. Altitude of territories wide ranging i.e. 400m up to 1800m.
Broader range of habitats frequented by juveniles and some adults in winter
i.e. dried riverbeds, river valleys.
Distribution.
Very common, where habitat is suitable, across the whole range of the study
area. Becomes more widespread in autumn and early winter as juveniles disperse
from breeding areas. Very few adults appear to vacate breeding territories in
early winter, but those that do are normally returned by December to early
January.
Population.
Minimum 400 pairs with likely maximum 500 pairs. Occupation of small niche
habitats contained and surrounded by highly adverse habitats i.e. woodland,
suggests healthy populations in residence at all suitable and primary sites.
Map
1. Black Wheatear . Collalba
Negra . Oenanthe leucura – Study Area Distribution
& Population Density Map
Movements.
Although some adults do move from breeding areas in late autumn and early
winter see under distribution, the ever presence of adults at most known
territories, indicate movement is largely confined to juvenile dispersal, with
most adults remaining site faithful during winter to extended breeding
territories. Birds are commonly seen at lower altitudes (river valleys etc.)
during winter and around human habitation i.e. village fringes, even the centre
of Ronda! No observations have been made of flocking or mass movements. Up to 8
individuals seen together and commonly 4 to 5 during postnatal period, these
being family parties. Juveniles tend to leave natal site around October, with
individuals returning during January to February, only to be displaced by
resident adults. Occupation of niche habitats surrounded by inappropriate
habitats i.e. Woodland, suggests wide ranging dispersal of juveniles displaced
and forced into secondary sites.
Stone Platform constructed by the male at the nest entrance |
Note: The above is a summary only and a part of an ongoing and incomplete survey.
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2 comments:
Lovely piece and a great study. Would you like some help for a week or so in May 2018? I'm an active ringer and walker - I know the Sierra de Grazalema reasonably well, but only the well trodden routes!
Hi Giles,
I am leading a tour the first half of May. I can give you some prime sites for seeing these beauties, if you would like to make a few observations? Peter
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